Preparation of emulsifiers for producing soluble oil



Nov. 22, 1955 M. R. LlPKlN 2,724,697

PREPARATION OF EMULSIFIEIRS FOR PRODUCING SOLUBLE OIL Filed July 18, 1952 Charge Oil sulfomflng Sulfonatian a Agent .i r H Sludge Separation Sludge Alkflli Neutralization Free-Oxygen Partial Containing Gas Oxldatlon Product (to Soluble Oil Manufacture) INVENTOR. MOSES ROBERT LIPKIN mitt fitwdh ATTORNEY United States Patent PREPARATION OF EMULSIFIERS F011 PRODUCING SOLUBLE OIL Moses Robert Lipkin, Havertown, Pa., assignor to Sun gil Company, Philadelphia, Pa., a corporation of New ersey Application July 18, 1952, Serial No. 299,597 8 Claims. (Cl. 252-332) This invention relates to the preparation of acidic derivatives of petroleum hydrocarbons. More particularly the invention is directed to the preparation of products comprising both petroleum sulfonates and hydrocarbon derivatives formed by partial oxidation of the hydrocarbons. Products of the invention have special utility in the manufacture of soluble oils.

The so-called soluble oils are employed commercially in metal working operations, such as cutting and grinding, and as spray oils, rust-proofing compositions and the like. In the manufacture of soluble oils a suitable mineral oil is compounded with emulsifying agents, and a minor amount of a solvent for both oil and water, generally referred to as a mutual solvent is usually added. As the emulsifying agents, petroleum naphthenates and mahogany sulfonates are often used in combination, the sulfonates also serving to enhance the rust-proofing characteristics of the composition.

It is known that suitable emulsifying agents for soluble oils can be prepared by liquid phase partial oxidation of petroleum stocks boiling in the lubricating oil or gas oil range. An example of a partial oxidation process of this type is disclosed in Johnson et al. Pat. No. 2,395,627. A disadvantage in producing emulsifiers in this manner arises, however, from the fact that the liquid phase partial oxidation reaction generally will not proceed properly if the charge stock contains the usual amount of aromatic constituents present in petroleum stocks. Aromatics inhibit the oxidation reaction and have the effect either of preventing any substantial amount of oxidation being obtained or, if sufiiciently drastic conditions are used to force the oxidation reaction, of causing the formation of resinous acidic products which are unsuitable for soluble oil manufacture. Also .various non-hydrocarbon constitu cuts of petroleum, such as sulfur and nitrogen compounds, may tend to inhibit the oxidation reaction. For this reason it has been necessary heretofore to pretreat the charge stock in order to reduce its aromatic content to a low value and perhaps also remove non-hydrocarbon constituents in order to avoid the inhibitory effect of these materials. This adds considerably to the expense of the operation.

The present invention is directed to and provides an inexpensive process for producing, from a single charge stock, a material containing both the mahogany sulfonates and the partial oxidation product emulsifiers desired for soluble oil manufacture. According to the invention, a charge stock containing a usual amount of aromatic constituents is first subjected to sulfonation to form mahogany sulfonic acids. After removal of sludge, the sulfonated stock is neutralized with an alkali and.the neutralized stock is then subjected to liquid phase partial oxidation to form carboxylic acid derivatives of the hydrocarbons. The resulting product, after neutralization with an alkali, is especially suitable for use in the preparation of soluble oil.

The first two steps of the present processsulfonation followed by neutralizationserve not only to produce mahogany sulfonates which are desired in the soluble oil composition, but also to convert aromatic constituents which would normally interfere with the partial oxidation reaction into a form in which no inhibitory effect is obtained. Furthermore, it has been found that the sulfonates formed upon neutralization of the sulfonated stock are stable under conditions employed in the oxidation step and do not therein undergo degradation affecting their quality. This would not be true, however, of the sulfonic acids before neutralization, as it has been found that they decompose rapidly under conditions used in the oxidation reaction. The neutralization step is accordingly essential.

The accompanying drawing is a simplified diagrammatic illustration of the present process. Charge oil for the process may be a petroleum distillate fraction boiling mainly above 450 F. such as a gas oil or lubricating oil cut. Selection of the charge stock with respect to boiling range will depend mainly upon the molecular weight desired for the carboxylic acids produced in the subsequent partial oxidation reaction. The charge stock may be a fraction as obtained directly from crude petroleum by distillation, or it may be an oil which has undergone treatment adapted to remove part of the aromatics, such as, for example, a rafiinate from a solvent extraction operation. In any event the charge stock should be a fraction which contains aromatic hydrocarbons in sufficient amount to yield the concentration of mahogany sulfonates desired in the product, such amount generally being in excess of 15% aromatics by weight.

Referring to the accompanying drawing, the charge oil is introduced to a sulfonation zone 10 wherein it is treated with any suitable sulfonating agent such as concentrated or fuming sulfuric acid, sulfur trioxide, chlorosulfonic acid and the like, sulfur trioxide being the preferred agent. Conditions for effecting sulfonation are well known, and any suitable conditions and procedure may be employed,

' with the operation being conducted batchwise or in continuous manner. Following the sulfonation step, the mixture is separated, as illustrated by separation zone 11, to remove the sludge comprising the so-called green sulfonic acids and any excess sulfonating agent. This may be done by allowing the mixture to settle in the same zone in which the sulfonation is efiected or in a separate zone, or it may be done in any other suitable manner such as by filtration or centrifuging.

After removal of the sludge, the oil containing the mahogany acids is neutralized as illustrated at neutralization zone 12. This may be done simply by mixing the acid oil with caustic soda or any other suitable alkali such as sodium carbonate or potassium hydroxide. It is important that the amount of alkali used be at least sufficient to neutralize substantially all of the mahogany acids formed so that the mixture which is subsequently oxidized will not contain any free sulfonic acids. An excess of alkali may be employed, if desired, so that the material charged to the oxidation step will be in alkaline condition, in which case the carboxylic acids will react with the excess alkali immediately as they are formed during the subsequent oxidation reaction.

The neutralized stock is then subjected to partial oxidation in liquid phase by means of a free-oxygen containing gas, as illustrated by zone 12. Conditions heretofore employed for partially oxidizing petroleum stocks of low aromatic content are suitable for oxidizing the sulfonatecontaining stock in the present process. A temperature of the order of 1l0165 C. generally should be employed and a preferred temperature range is l20150 C. The oxidizing medium may be air or other gas comprising free oxygen; and for the present purpose ozone can be considered the equivalent of a free-oxygen containing gas. The reaction can be efiected without a catalyst, but

it is usually preferred to utilize a suitable catalyst, such as a naphthenate, oleate or stearate salt of manganese, magnesium, cobalt, lead, copper or the like, in order to accelerate the. rate of reaction, Theoperationcan be conducted at atmospheric pressure or an elevated pressure maybe used-to increase the reaction rate.

The level to;which,the oxidation reactionshould be carried will depend upon the particularmanner in which it is desired toutilize the product in compounding the soluble oil. In one. manner of operation the oxidation may be effected just to that degree corresponding to the desired carboxylic acid salt content of the soluble oil, soqthat the preparation of the soluble oil will comprise merely neutralizing the oxidation acidsand, if desired, blending the neutralized product with a mutual solvent. In such case the sulfonation reaction preceding the oxidation should also be eifected to a degree corresponding to the-desired sulfonate content of the soluble oil. In another mannerof operation both the sulfonation and oxi dation reactions are carried to higher levels, in which case theproduct constitutes a concentrate of the two,

emulsifying agentswhich is subsequently blended with oil to form soluble oil having the desired sulfonate and carboxylic acid salt contents. Regardless of which procedure is used, the degree to which the sulfonation is carried generally will correspond to a mahogany sulfonic acid content within the range of 225% by weight of the acid oil, while the degree of oxidation generally will fall within a range corresponding to a saponification value of 15l00 mg. KOH/gram of the oxidized product.

The following example specifically illustrates the process according to the invention:

Charge stock for the process was a lubricating oil rafiinate obtained from. a furfural extraction operation and having the following characteristics:

Viscosity 100 F., CS; 127 Viscosity @"210" F., CS 9.56 Refractive index, 20 C./D 1.4991 Density, 20 /4 C 0.9118 Viscosity-gravity constant 0.855 Viscosity index 35 Average molecular weight; 410 Aromatic content, Wt. per cent 27 It was found that this stock could not be oxidized substantiallyunder customary partial oxidation conditions due, to the inhibiting effect of the aromatics; and that when more severe oxidizing conditions were employed, resinous oxidation products not suitable for soluble oil manufacture were formed.

The foregoing stock was sulfonated by contacting it at ordinary ambient temperature with S03 until the acid oil contained about 14% mahogany acids by weight. About 12% by weight of green acids was also formed and this material was separated from the reaction mixture as a sludge by centrifuging. Upon attempting to oxidize a portion of the acid oil, it was found that charring and coke. formation occurred rapidly, indicating serious decomposition of the mahogany acids.

A500 gram portion of the acid oil was exactly neutralized with caustic soda and then was mixed with 0.4% manganese oleate as an oxidation catalyst. The mixture was partially oxidized in a 2" I. D. steel column at a temperature of about 138 C. by bubbling air upwardly through the column until the mixture had a saponification value of about 52 and an acid number of about 16. The resulting product, upouneutralization with caustic soda, constituted an emulsifier concentrate suitable for blending With hydrocarbon oil'to produce a soluble oil:

I claim:

1. Method of forming an acidic partial oxidation prodnot containing mahogany sulfonates and suitable for use in preparing soluble oil which comprises treating a petroleum oil boiling mainly above 450 F. with a sulfonating agent under sulfonating conditions, separatingsludge from the sulfonated stock, neutralizing. the sulfonated stock with an alkaline-reacting alkali metal compound, and treating the neutralized stock in liquid phase with'a freeoxygen containing gas under conditions, includinga temperature above C., effecting partial oxidation to carboxylic acids.

2. Method according to claim 1 wherein the sultonation is effected to a degree corresponding to a mahogany sulfonic acid content in said sulfonated stock of 225% by weight.

3. Method according to claim 2 wherein thepartial, oxidation is effected to a degree corresponding, to a.

saponification value of 15-100 mg. KOI-I/gram.v

4. Method according to claim 1 wherein the partial oxidation is effected to a degree corresponding to a saponification value of 15100 mg. KOH/gram.

5. Method of forming. a soluble oil which comprises treating a petroleum oil boiling mainly above. 450 F.

with a sulfonating agent under sulfonating conditions, separating a sludge from the sulfonated stock, neutralizing the sulfonated stock with an alkaline-reacting alkali metal compound, treating the neutralized stock in. liquid phase I with a free-oxygen containing gas underconditionstineluding a temperature above 110 C., effectingpartial oxidation to carboxylic acids, and neutralizing the partially oxidized stock with an alkaline-reacting alkali metal compound.

6. Method according to claim 5 wherein both the sulfonationand partial oxidation are effected to degrees.

corresponding, respectively, to the desired sulfonate and carboxylic acid salt contents of the soluble oil.

7. Method according to claim 5 wherein both the sulfonation and partial oxidation are effected to degrees in excess of those corresponding to the desired sulfonate and carboxylic acid salt contents of the soluble oil, and said soluble oil is formed by blending hydrocarbon oil with the partially oxidized stock.

8. Method of forming an acidic partial oxidation prod not containing mahogany sulfonates and suitable for use in preparing soluble oil which comprises treating. a petroleum lubricating oil stock with a sulfonating agent under sulfonating conditions until the stock, after separation of sludge, has a mahogany sulfonic acid content of 2-25% by weight, separating sludge from the sulfonated stock, neutralizing the sulfonated stock with an alkalinereacting alkali metal compound, and treating the neutralized stock in liquid phase at a temperature of 110-165 C. with a free-oxygen containing gas until the stock has a saponification value of 15-100 mg. KOH/ gram.

References Cited in the fileof this patent UNITED STATES PATENTS 1,436,214 Teichner Nov. 21, 1922 1,817,599 Adams Aug. 4, 1931 2,361,476 Higbee Oct. 31, 1944 2,454,826 Liberthson Nov. 30, 1948 2,454,827 Moscowitz Nov. 30, 1948 

1. METHOD OF FORMING AN ACIDIC PARTIAL OXIDATION PRODUCT CONTAINING MAHOGANY SULFONATES AND SUITABLE FOR USE IN PREPARING SOLUBLE OIL WHICH COMPRISES TREATING A PETROLEUM OIL BOILING MAINLY ABOVE 450*F. WITH A SULFONATING AGENT UNDER SULFONATING CONDITIONS, SEPARATING SLUDGE FROM THE SULFONATED STOCK, NEUTRALIZING THE SULFONATED STOCK WITH AN ALKALINE-REACTING ALKALI METAL COMPOUND, AND TREATING THE NEUTRALIZED STOCK IN LIQUID PHASE WITH A FREEOXYGEN CONTAINING GAS UNDER CONDITIONS, INCLUDING A TEMPERATURE ABOVE 110* C., EFFECTING PARTIAL OXIDATION TO CARBOXYLIC ACIDS. 